"Environmented" electronic systems

1. "Environmented" electronic systems • Deposited clusters or molecules: • on rare gas surface -> "soft-landing" • FeN @ Ru via Ar • [Lau et al., Low Temp. Phys. (2003)] • thymine @ Ar @ Pt • [Levesque et al., Nucl. Instr. Meth. Phys. Res. (2003)] • on oxides (MgO,ZnO,Al2O3,…) -> catalysis studies

2. "Environmented" electronic systems • Embedded clusters • in rare gas droplets • -> control of • temperature,size • [Bartelt et al., PRL (1996)] Ag3+ @ Ar • in rare gas matrices • -> "inert" (?) environment • [Lecoultre et al., JCP (2007)] • [Bonacic-Koutecky et al.,JCP (1999)] free Ag3+

3. Dynamics of extended systems Dynamics model-potential (frozen) electrons Car-Parrinello MD All classical charge creation MM / QM(TDDFT) TDDFT-MD MM/QM(TDCI) TDCI Environment Electrons e- quantal but small systems environment e- excitation  charge creation  e- quantal but in ground state electronic excitation How ??

4. static parameters • staticpolarization • no e- response of MM Standard QM/MM QM: quantum chemistry MM: classical force fields stretching folding twist electrostatic d+ d- Van der Waals

5. Generalized MM: explicit dynamical dipoles e- response from MM x no e- emission Generalized QM/MM NaN Electrons • VdW • ab initio + • fine-tuning soft Coulomb Rion Ar, Ne, Kr MgO DAr RMg2+ RAr add new terms in Uext RO2- • Lennard-Jones • soft Coulomb • oscillators DO2- • Buckingam • soft Coulomb • oscillators frozen cores Madelung potential

6. (Time-resolved) observables During or after cluster deposition, laser irradiation, … from electrons: • dipole response (-> spectral analysis) • ionization • number of emitted e- • kinetic E spectrum of emitted e- • angular distribution of emitted e- from ions: • potential and kinetic (temperature) E • global deformation and shape from matrix: • potential and kinetic (temperature) E • global deformation and shape • internal excitation (dipoles)

7. I II Guided tour example of deposition Cluster properties Optical response Photoelectrons III Deposition dynamics Energies Site deposition Role of charges Matrix properties Global excitation Internal excitation

8. z y x Optical response Na6 on MgO(100) oblate Na8 in Ar164 short–range compression long –range polarization final blue-shift broken x-y degeneracy g geometry Laudau fragmentation g core repulsion subtle balance core repulsion vs. polarization attraction

9. Polarization Caution: "heliumblue-shift" Exp: Rostock Compression Optical response embedded clusters Rare gas not that inert…

10. Photoelectron angular distributions w=5.44 eV laser pol. Na8 IP=-4.3 eV I = 109 Wcm-2 FWHM = 20 fs MgO (or Ar) no problem of orientation no state dependence !

11. Photoelectron angular distributions free orientated Na8 state PAD, w=2.6 eV No orientation problem but… complex interactions with surface ! Na8 @ MgO total PAD, 3 w suppression towards surface Na8 @ Ar total PAD, 2 w

12. Cluster Electrons Ions Matrix Cores Shells I II Guided tour example of deposition Cluster properties Optical response Photoelectrons III Deposition dynamics Energies Site deposition Role of charges Matrix properties Global excitation Internal excitation

13. Na+ @ Ar384 Ekin0= 136 meV Charged atom deposition Inclusion of Na+ in a dynamically created Ar vacancy fixed layers Na: slight minimum Na+: deep minimum thanks to Ar vacancy

14. Deposition of Na dimers • Na+ @ Ar384 • Na @ Na+/Ar383 Na2+ @ Ar384 Na2 @ Ar384 more robust attachment when charged

15. Cluster Electrons Ions Matrix Cores Shells I II Guided tour example of deposition Cluster properties Optical response Photoelectrons III Deposition dynamics Energies Site deposition Role of charges Matrix properties Global excitation Internal excitation

16. Dipole d.o.f Na6 deposition, Ekin0 = 136 meV/ion fixed Ar cores fixed Ar dipoles full Ar dynamical dipoles = crucial ingredient for cluster dynamics

17. Ar electronic response Na6+ Na+ Eexcµ d2 Ekin0 = 136 meV/ion at impact… 16 meV 9 meV Na+ Na6+ charge effect >> size effect Na6 Na 0.2 meV 1.2 meV Na Na6

18. Time evolution of dipoles Ekin0 = 6.8 eV NaQ @Ar Ekin0 = 136 meV Q= 0, +1, -1 NaQ Ar atoms Ar dipoles Q= -1 Q= 0 Q= +1 • Important effect of charge • Q = 0 ahigh Ar excitation energy • Threshold for reflection: • factor 20 between Na+ and Na Dipoles ?

19. Dipole localization Na6+@Ar384 Ekin0 = 800 meV/ion Impact Radial dipole distribution at different times Initial • Localized excitation • Sizeable dipole "noise" • Moderate time evolution Longer time

20. Conclusion and perspectives • Clusters and molecules @ environment • Hierarchical approach for a generalized QM/MM • Nan@Ar,Ne,Kr done • Nan@MgO done • dynamical electronic response of substrate • Nan@MgO with defects in progress • C,N,O,H @ H2O in near future • C,N,O,H @ H2O @ rare gas in future M. Farizon L. Sanche

22. Context and motivations • Clusters deposited on surface embedded in matrix (nano)technologies surface engineering Exp Theory free • Particular interest: raregas substrates (Ne, Ar, Kr) • « soft-landing » • AgN @ Pt(111) via Ar • Bromann et al., Science 274, (1996) 956 • FeN @ Ru(001) via Ar • Lau et al., Low Temp. Phys. 29 (2003) 296

23. Context and motivations AgN+ codeposited with Ar @Au Harbich et al., PRB 76 (2007) 104306 fluorescence Ag1@Ar • NeutralizationofAgN+by • e-fromAu then • goingthrough Ar • non trivial electroniceffect of Ar matrix luminescence Ag1+@Ar@Au

24. Na6 deposited on MgO structure mismatch energy dependence site dependence

25. Réponse optique Na8@Ar434 Na83+@Ar434 hw = 1.9 eV I = 2×1012 W.cm-2 Δt = 50 fs (FWHM) initial • élargissement vers le rouge • en accord avec exp Seifert et al., Appl. Phys. B 71 (2000) 795